The Spotted Eagle Ray. 



293 



teeth, the 4 anterior are deeply worn, the enamel of the outermost one being 

 nearly gone. The lower plate is 6 inches long and 2 wide. It has 21 teeth, 

 of which the anterior 10 show much wear, there being a noticeable depression 

 over Nos. 6, 7, 8, and 9. 



These teeth-plates being freed from the jaw cartilages, it is easy to see 

 that the lower plate is gently curved with the convexity upward, while the 

 upper plate is sharply bent with the convexity downward. Thus the ante- 

 rior edge of the upper plate strikes the lower about one-third of the distance 

 back from its point, and for this reason the lower jaw projects beyond the 

 upper by some 5 or 6 teeth generally, and this also accounts for the worn place 

 in the lower plate as noted above (see figs. 22 and 23, plate ix). In all these 

 Florida specimens the lower tooth-plate projects beyond the lower lip by the 

 width of one tooth, and this tooth is free from the underlying cartilages. 



In the ten specimens of lower jaws here described and in the other two 

 examined but never excised from the fish, all had the teeth v-shaped, as 

 shown in the photograph and the drawing (fig. 23, plate ix, and text-fig. 14) ; 

 none had the teeth "nearly straight," as described by Gunther (1870), or 

 "teeth of the lower jaw straight or more or less angularly bent," according 

 to Jordan and Evermann (1896), or teeth transverse and not pointed in the 

 lower jaw, as found by Annandale (1910) in 

 specimens from the Bay of Bengal, or teeth 

 obtusely rounded in front as shown by Cuvier 

 and noted by others, especially Miranda Ri- 

 beiro (1907). 



In my specimens not only does the lower 

 jaw project beyond the upper, but each tooth 

 in it projects beyond the next one behind; 

 thus, seen from above, each tooth overlaps 

 the next one in front like shingles or tiles in 

 a roof. The amount of overlapping is cer- 

 tainly equal to and generally somewhat Text-fig 

 greater than the width of the tooth. It should 

 be noted here that the soft, pulpy teeth at 

 the hinder end of the jaw are slightly wider than the hard bony ones in 

 front. By reference to the figures of the jaws it will be seen that the 

 ends of the upper teeth are curiously bent backwards, giving each indi- 

 vidual tooth the form of a very fiat bow (text-fig. 15). Careful mea- 

 surements of every set of teeth in my possession reveal the interesting 

 fact that the length of the upper teeth measured between the points at 

 which the outer bends begin is in every case exactly equal to the width of 

 the lower jaw-plate of that set. Close inspection of these teeth plates shows 

 that in the region of these bends there is a slight depression transverse to 

 the long axis of each tooth. This forms a shallow, longitudinal groove on 

 each side of the upper jaw-plate, and, as noted above, accurately marks off 

 the width and place of contact of the lower jaw. The worn surface of the 



15. — Upper tooth-plate 

 oi an A'etobatus narinari, from 

 Key West, Florida, 19 13. 



